The machine pictured above is the 1-BA machine.
It was made by Gray, for Western
Electric, used drums covered with the same material used on recording tape, and
the heads moved across on a lead screw. They were
tube units. Same stuff that was used
in the portable battery powered radios of the era, directly heated filaments
for quick turn-on with 2 subminiature tubes similar to the hearing aids of the
era for the first stages of amplification, and the radio tubes
for the power amps and bias
oscillator!
The Western Electric model WE1A answering
machine was the first answering machine (not shown). Recording was done on a
drum with a magnetic coating. It looks like standard recording tape,
except the magnetic surface was about 1/8" thick. There were two drums
mounted on a common shaft. They were about 3" in diameter. The
outgoing announcement drum was about 1" long and could record a 30 sec
announcement, and the incoming message drum was about 8" long and could
hold 30 messages. Each message was about 60 seconds long (not confirmed).
Five tubes were used in the electronics. Three 7-pin miniatures and two hearing
aid type tubes.
Each machine weighed about 50 pounds and, like all Western Electric
equipment, was over engineered to last forever.
